Automatic test equipment (ATE) is generally an apparatus or system that performs tests on a device under test (DUT) to detect defects or errors in the DUT in an automated fashion. ATE may be used for memory testing to detect faults caused by an error in a memory manufacturing process in various ways, for example through the use of ATE prior to completion of memory chip packaging to detect errors such as defective passive elements. In memory test equipment such ATE, a test pattern may be reproduced using an algorithmic pattern generator (ALPG) to test a memory. For memory testing, ALPG test patterns are used by the ATE to detect defects or errors in the DUT.
Mount testing generally refers to testing a DUT that has been installed or mounted, such as memory device or chip that has been mounted on a printed circuit board (PCB) in a memory module. In mount testing, a test application may be loaded into a processor to test the memory. Mount testing may be used to detect or identify various problems, such as poor operating characteristics and/or defective active elements in the DUT. Mount testing may differ from testing an un-mounted device, such as a semiconductor memory device on a wafer or in an un-mounted package, because the semiconductor memory devices may be operating.
Test equipment can be expensive, such as ATE costing millions of dollars. There can be benefits from improvements to test equipment and test methods, for example enabling or expanding or speeding up the automated test of devices such as high-speed memories. Enabling ATE to provide high speed automated testing that otherwise may be performed using mount testing, which generally is slower than ATE testing, can provide significant benefits such as providing for improved quality and decreased costs for semiconductor memory devices.